Although some studies have focused on the role of exercise on inflammation and cytokine expression in cancer patients undergoing treatment and survivors, to our knowledge none have investigated the effect of exercise during neoadjuvant treatment as a complementary therapy to 1) modulate inflammation which may have a positive influence on chemotherapy response and 2) preserve or improve skeletal muscle, thus preventing cancer cachexia. Furthermore, we believe that the neoadjuvant treatment period could be a window of opportunity to optimize patient's nutritional status before surgery, which until now has been under used. Bearing in mind that nutritional interventions may also influence IL-6, our hypothesis is that a Combined Exercise and Dietary Intervention (CEDI) may induce positive alterations in cytokine profile and increase NK cell infiltration of the tumor in gastric and pancreatic cancer patients submitted to neo-adjuvant therapy.